During the last decade substantial research efforts have resulted in significant progress in defining the pathologic changes of MS, using MRI techniques to evaluate disease progress, and developing disease modifying medications (Joy &Johnston, 2001). However, we still know very little about the natural history of MS over time and can offer persons with MS little guidance about the likely outcome of their disease or ways that their individual behaviors might influence the trajectory of disease-related limitations and disability. Findings from the current study (2R01NRO3195 06-10) indicate that the trajectory of change over time (7 years) in MS-related functional limitations and quality of life outcomes (perceived quality of life, depression, secondary conditions) is slow but significant and in a direction reflecting increased limitations and secondary conditions. Findings from the current study support the hypothesis that health promoting behaviors are able to mediate the effects of illness related limitations on perceived quality of life in community residing persons with MS. The primary purpose of this competing continuation is to identify psychosocial and behavioral factors that may influence the trajectory of functional limitations, disability and quality of life in persons with MS through continuing longitudinal follow-up of the existing sample (N=565). The explanatory model of health promotion and quality of life in chronic illness that was developed, refined and validated over 10 years of earlier work (R29NR03195 and 2R01NR03195) will be integrated with the well known disablement process model (Verbrugge &Jette, 1994) to obtain a better understanding of factors affecting the trajectory of MS related functional limitations and disability and how these variables are subsequently related to changes in quality of life. We will also explore how perceptions of aging and co-morbid conditions commonly experienced with aging may influence the progression of functional limitations and disability over time as this sample (average age 54) ages with a chronic disabling condition. We will enhance the methods used in our current study by incorporating performance-based measures of functional limitation to obtain a more complete understanding of varying clinical expressions of MS limitations over time. Longitudinal data will be analyzed with hierarchical linear models (HIM) and structural equation modeling techniques.